Starter clutch



Oct. 9, 1962 w. ov 3,057,212

STARTER CLUTCH Filed July 11, 1960 5 Sheets-Sheet l FIG. 4. FIG. 5.

W/LHELM HOVE/V INVENTOR A TTORNEY 9, 1962 w. HOVEN 3,057,212

STARTER CLUTCH Filed July 11, 1960 5 Sheets-Sheet 2 FIG. 2.

FIG. 3.

-l- W/L HELM HOVE/V 1 INVENTOR Arrokn/sv W. HOVEN STARTER CLUTCH Oct. 9,1962 5 Sheets-Sheet 3 Filed July 11, 1960 INVENTOR A ORNEY J W/LHE'LMHOVE/V mm .wb k. MM Nb United States Patent 3,@57,212 TARTER CLUTQHWilhelm I-ioren, Wurselen, Germany, assignor to Garbe, Lahmeyer & Co.Aktiengesellsehaft, Aachen, Germany Fiieri July 11, 1960, er. No. 42,129Claims priority, application Germany July 13, 1959 Claims. (Cl. 747)This invention relates to a starter clutch and more particularly toapparatus, commonly known as a Bendix clutch, arranged to connect anddisconnect a starter motor to an internal combustion engine.

In the operation of internal combustion engines, particularly those usedin automobiles, it is common practice to provide a device to connect thestarter motor to the engine in such a manner that the connectiondisengages when the engine starts up, despite the fact that the startermotor may still be revolving. This apparatus has consisted in the pastof a sleeve which has an internal high-pitch thread engaging the startermotor drive shaft and which has an external pinion gear engaging anenginedriving ring gear. When the engine rotates faster than the motor,the sleeve is moved by the thread in such a way that the pinion is drawnout of engagement with the englue-driving gear. With such a startingmotor arrangement, it has been found necessary to place the pinion onthe motor shaft externally of the motor housing; this is done so thatthe adjacent bearing for the motor shaft is protected from dirt. Oneresult of this arrangement is that the motor bearings are relativelyclose together, making it possible to construct the motor with acomparatively small air gap and with high efficiency. The maindisadvantage of this well-known arrangement is that the cantileverposition of the forces on the free end of the shaft brings aboutstresses in the bearing and early failure. Also, with the knownconstruction the starter motor has been driven at engine speed for shortperiods of time, thus subjecting the hearings to excessive wear. Theseand other difiiculties experienced with the prior art devices have beenobviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide astarter clutch adapted to be located between the starter motor bearingsinstead of externally of them.

Another object of this invention is the provision of a starter having aclutch arrangement that is capable of a long life of service with aminimum of maintenance.

A further object of the present invention is the provision of a starterclutch, the major part of which is not exposed to foreign matter and maybe properly lubricated.

It is another object of the invention to provide an engine starterarrangement in which the starter motor bearings are not subjected tostress in excess of that experienced at idle speed.

With these and other objects in view, as will be apparent to thoseskilled in the art, the invention resides in the combination of partsset forth in the specification and covered by the claims appendedhereto.

The character of the invention, however, may be best understood byreference to certain of its structural forms, as illustrated by theaccompanying drawings in which:

FIGURE 1 is a sectional view of a device embodying the principles of thepresent invention;

FIGURE 2 is a sectional view of another version of the invention;

FIGURE 3 is a partially-sectioned end view of the apparatus shown inFIGURE 2;

FIGURE 4 is a sectional view of the invention taken on the line IV-IV ofFIGURE 3;

FIGURE 5 is a sectional view of a portion of the invention; and

FIGURE 6 is an exploded view of the invention.

In general, the invention consists of a starter motor arrangement inwhich the starter clutch slides along the motor shaft and has its outersurface mounted in a bearing in the motor housing. At the same time, thepinion is mounted on a sleeve that is carried in a needle-rollerunidirectional clutch mounted inside the clutch. The inventioncontemplates that the outer sleeve of the starter clutch be considerablyelongated to surround the threaded bushing; the outer sleeve of theclutch and the threaded bushing are connected by splines and the clutchunit is almost completely enclosed within the starter motor housing. Inorder to reduce the outside diameter of the clutch, the rollers of theneedle clutch are contained in a common cage and are prestressed.Furthermore, a spring means is interposed between the pinion sleeve andthe threaded bushing to absorb shock and vibration.

Referring first to FIGURE 1, wherein are best shown the general featuresof the invention, the starter clutch, indicated generally by thereference numeral 10, is shown in use in a starter motor 11 having ahousing 12, a stator 13, and a rotor 14 with a shaft 15. Mounted in thehousing 12 concentrically of the shaft 15 is a bearing 16; the starterclutch 10 is rotata-bly and slidably mounted in this hearing. Thestarter clutch consists generally of an outer sleeve 17, a threadedbushing 18, and a pinion sleeve 19. The inner bore of the threadedbushing 18 is formed with a worm groove 21 which engages a similar wormthread 22 of high pitch formed on the surface of the motor shaft 15. Anaperture 23 extends through the bushing and carries a detent ball 24which engages a groove 25 formed in the surface of the motor shaft. Theouter surface of the bushing is provided with spline ribs 26 which areslidably engaged with spline grooves 27 formed on the inner surface ofthe outer sleeve 17. A suitable detent sleeve 28 surrounds the inner endof the threaded bushing 18 and contacts not only the surface of themotor shaft but also an outer cylindrical surface of the bushing. Thepinion sleeve 19 extends from the motor housing 12, as does the shaft15; the outer end of the sleeve is provided with a pinion 29 which isadapted to engage or disengage a driving ring gear 31 of an internalcombustion engine, not shown. The outer end of the shaft is providedwith a stop 32 to limit the axial travel of the pinion sleeve. Thesleeve is formed at its outer end with a bore 33 in which is located abushing 34 which is slidable along the motor shaft 15. Entering theother end of the pinion sleeve is a counterbore 35 in which lies a coilspring 36; the end of the counterbore is provided with a retaining ring37 which holds the spring in place. It will be understood that the endof the spring closest to the bottom of the counterbore is suitablyfastened to the shaft 15 and does not move with the pinion sleeve. Thesleeve 19 is provided with a smooth cylindrical outer surface 38 and theouter sleeve 17 is provided with a smooth cylindrical inner surface 39,the surfaces 38 and 39 being concentric with the axis of the shaft andbeing spaced to provide an annular space. In this last space is a cage41 holding a series of long, thin rollers 42, the cage and rollersconstituting with the enclosing members a one-way clutch. The pinionsleeve 19 is fastened against axial movement outwardly of the outersleeve 17 by a snap ring 43, while the threaded bushing 18 is similarlyfastened to the outer sleeve 17 by a snap ring 44 to limit outwardmovement.

The operation of the invention will now be readily understood in view ofthe above description. When the starter button (on an automobile) ispressed, the detent sleeve 28 is moved in a conventional manner and thedetent ball 24 moves through the aperture 23 and out of the groove 25.The starter motor 11 is energized and the rotor 14 rotates relative tothe stator 13. The rotation of the stator and the shaft 15 acts throughthe worm thread 22 and the worm groove 21 to move the threaded bushing18 axially along the shaft; relatively little rotation of the bushingtakes place because of the generous lead of the thread. As the bushingmoves along the shaft, it carries with it the outer sleeve 17 and thepinion sleeve 19 because of their interconnection. Eventually, the outerend of the pinion sleeve and the pinion 29 strike the stop 32; afterthat the rotation of the shaft is transmitted directly to the pinionwhich, in turn, engages and rotates the ring gear 31 so that theinternal combustion engine is turned over. When the engine starts andspeeds up, it drives back through the driving gear 31 which then drivesthe pinion 29 instead of the reverse action as was previously true. Thehigh-speed rotation of the pinion is transmitted to the pinion sleeve,the outer sleeve, and the threaded bushing; the rotation of the bushingat a rate faster than the shaft causes the bushing to move axially backto its original position and, because of its interengagement with theworm groove 21 and the worm thread 22, these other elements move withit. The coil spring 36 had previously resisted the movement of thepinion sleeve toward engagement with the stop 32, but now assists themovement in the other direction. Because of the interposition betweenthe pinion sleeve 19 and the outer sleeve 17 of the one-way clutchformed by the cage 41 and the rollers 42, the fact that the pinionsleeve may be rotated very rapidly by the engine does not bring about asimilar rapid rotation of the outer sleeve 17 after the initial returnphase. As a matter of fact, the sleeve continues to rotate only at thespeed of the normal idling speed of the starter motor, so that thebearing 16 is not subjected to excessive wear.

Referring now to FIGURE 2, wherein is shown another embodiment of theinvention, the starter clutch, indicated generally by the referencenumeral 50, is shown as consisting of a threaded bushing 51, an outersleeve 52, and a pinion sleeve 53. The threaded bushing is provided witha detent aperture 54 and an internal worm groove 55; external splines 56engage similar axial grooves 57 formed on the inner surface of the outersleeve 52. The pinion sleeve 53 has an external pinion 58 and aninternal supporting bushing 59; it is also formed with a counterbore 61in which is located a coil spring '62 whose right hand end is adapted tobe fastened to the motor shaft. A locking ring 63 is located in theinner end of the counterbore and holds the coil spring in place. Betweenthe pinion sleeve and the outer sleeve is a one-way clutch made up of acage 64 and rollers 65. Snap rings 66, 67, and 68 serve to lock thepinion sleeve, outer sleeve, and the threaded bushing together. A seriesof V-shaped wire springs 69 are connected at one end to the cage 64 andlie within the grooves 57 in the outer sleeve. A pair of Bellevillesprings 71 and 72 are interposed between the threaded bushing and thepinion sleeve.

FIGURE 3 shows particularly well the manner in which the cage 64 and therollers 65 cooperate with the grooves 57 in the outer sleeve 52 to forma one-way clutch. The bottom surfaces of the grooves are inclinedslightly, so that when the sleeve 52 rotates ahead of the sleeve 53, therollers are jammed between the bottom surfaces of the grooves and theouter surface of the sleeve 53 and a driving connection is made; whenthe sleeve 53 rotates ahead of the sleeve 52 (as when the internalcombustion engine starts and picks up speed), the rollers are looselyheld and do not provide a driving connection. This disengagement is notcompleted, however, until the engine has caused the return movement ofthe clutch to its original position.

FIGURE 4 shows the manner in which the wire spring 69 is used toprestress the one-way clutch. FIGURE is a sectional view through thecage 64; as indicated, it is provided with annular rims 73 and 74between which ex tends a tubular member 75 which is provided withgenerally rectangular apertures 76, which (as is evident in FIGURE 3)have inclined edges.

FIGURE 6 is an exploded view of the embodiment of the invention shown inFIGURE 2. This view shows particularly well the manner in which the rim73 of the cage 64 is notched to fit the splines 57 on the inside of theouter sleeve 52; such notches are not necessary on the rim 74, since itresides in a portion of the sleeve beyond the splines.

The operation of this embodiment of the invention is substantially thesame as in the version described in connection with FIGURE 1 and theadvantages are similar. For instance, the wear on the bearing in themotor housing is reduced. Also, the starting motor itself is sparedconsiderable wear by the use of the present invention; while in theprior art devices the motor shaft was supported in a bushing connectedwith the pinion, the support is now provided by the outer sleeve 52 ofthe starter clutch. In the previously-known constructions, the pinion,when driven at high speed by the engine, speeded up the motor rotor farbeyond its usual speed through friction of the overdrive; the motorhousing hearing was thus under the strain provided by the full speedoperation of the pinion. According to the present invention, however,the rotor is not forced to a speed of rotation beyond its idling speed,due to the reduced friction in the overdrive arrangement. The bearing inthe motor housing is subjected only to the stress encountered at theidling speed of the motor and its friction serves to prevent speed-up ofthe rotor. The wire spring 19 maintains a peripheral preloadiug of theover-running one-Way clutch and maintains the rollers '65 in the narrowportions of the grooves 57, so that the driving action is instantaneous.The Belleville springs 71 and '72 absorbs the shock of the pinion sleeve19 striking the stop 32; this has the eifect of reducing noise andvibration during the operation of the device.

It is obvious that minor changes may be made in the form andconstruction of the invention without departing from the material spiritthereof. It is not, however, desired to confine the invention to theexact form herein shown and described, but it is desired to include allsuch as properly come Within the scope claimed.

The invention having been thus described, what is claimed as new anddesired to secure by Letters Patent is:

1. A clutch for a starter motor, comprising (a) a housing in which themotor is mounted,

(b) a motor shaft extending from the motor and having a free end,

(c) a bearing mounted in the housing and extending around the shaftadjacent the said free end thereof,

(d) a threaded bushing mounted on the shaft and having threadedengagementtherewith,

(e) a pinion sleeve also mounted on the shaft for freesliding movementthereon,

(f) an outer sleeve extending around substantial portions of thethreaded bushing and the pinion sleeve in sliding driving relationshipwith the threaded bushing, the outer sleeve having a smooth cylindricalouter surface which is rotatably and slidably carried within the saidbearing, and

(g) a one-way roller-type clutch extending radially between the pinionsleeve and the outer sleeve and connecting the two sleeves in operativedriving relation in one direction only of relative rotation.

2. A clutch as recited in claim 1, wherein the outer sleeve is connectedby axial splines to the threaded bushing.

3. A clutch as recited in claim 2, wherein the oneway clutch includes acage, elongated rollers in the cage, and cam-shaped grooves formed inthe outer sleeve in which grooves the rollers reside.

4. A clutch as set forth in claim 3, wherein means is provided topre-stress the cage and rollers so that the rollers normally bring aboutimmediate power transfer between the outer sleeve and the pinion sleeve.

References Cited in the file of this patent UNITED STATES PATENTS CarleSept. 10, 1935 6 lanes Ian. 3, 1939 Sabatini Oct. 29, 1957 Sabatini Jan.7, 1958 Schneider et a1. Dec. 2, 1958

